NSX PreCheck Warning for (DLB) Distributed Load Balancer while upgrading to VCF 9.1

Products

• VMware NSX
• VCF Operations

Issue/Introduction

• When performing pre-checks for an upgrade to VMware Cloud Foundation (VCF) 9.1, administrators encounter the below NSX precheck warnings if a Distributed Load Balancer (DLB) is currently configured in the environment.

Found data inconsistencies: Default distributed load balancer instance is not supported in VCF 9.1 release. Please update the distributed load balancer to attach to a group


Found data inconsistencies: Unsupported features for distributed load balancer in VCF 9.1, e.g. error log level, access log, persistence profiles, are configured and will be reset after upgrade.

Found data inconsistencies: The following features cannot be configured for distributed load balancer in VCF 9.1: error log level, access log enabled, persistence profiles.

• This warning surfaces because certain DLB features have been modified or deprecated in the VCF 9.1 release.

• Depending on the current configuration, the precheck will display one or more of the following messages:

  • Traffic Disruptions: Notifications that traffic disruptions or connection resets on the Distributed Load Balancer will occur during the NSX upgrade on ESXi hosts.

  • Unsupported Features: Warnings that specific features—including error log level, access log enabled, and persistence profiles—are no longer supported for DLBs in VCF 9.1. If currently configured, these settings will be automatically reset after the upgrade.

  • Unsupported Default Instance: A notification stating that the default DLB instance is not supported in VCF 9.1, prompting to update the DLB to attach to a group.

Environment

VMware NSX 9.x

Cause

These precheck warnings are expected behavior due to feature architecture changes in the VCF 9.1 release.

Resolution

No direct corrective action is required to clear the precheck. To continue with the upgrade, follow the below guidelines:

1. Acknowledge and Proceed: Safely acknowledge the warnings in the precheck UI and proceed with the VCF 9.1 upgrade.

2. Plan for Temporary Traffic Disruption: Be aware that temporary traffic disruptions or connection resets will occur on the DLB while the NSX components on the ESXi hosts are upgrading. Traffic processing will automatically recover once the host upgrade completes. Client applications may need to retry connections if traffic drops during this window.

3. Post-Upgrade Configuration Changes: Once the upgrade to 9.1 is complete, you will no longer be able to configure Virtual Server access logs, DLB persistence profiles, or DLB error log levels. Any prior configurations for these features will be reset. (Note: If you are utilizing the default DLB instance, you will need to attach it to a specific group to align with VCF 9.1 requirements).